Lithium chloride (LiCl) has widespread commercial application. It is used in the production of lithium metal, lithium carbonate and lithium hydroxide monohydrate for various battery applications. Due to the requirement for high purity in many of these applications, particularly when used as a cathode material in lithium ion batteries, there is an ever increasing need for high purity lithium chloride.
Traditionally, LiCl from a brine source is purified by solar evaporation technology to concentrate the brine solution and thereby remove magnesium, sodium and potassium impurities. Other impurities, such as boron, may be removed by solvent extraction technology, whereas traces of calcium, magnesium and other similar impurities may be removed by increasing the pH of the brine solution and also through the addition of soda ash and the formation of insoluble calcium carbonate. This is very time consuming and highly dependent on the weather. Therefore, a purification means is needed to remove the majority of the impurities from a LiCl solution derived from a brine source, such that the concentration of each impurity is reduced to less than about 20 ppm.
An impurity concentration of less than about 20 ppm makes the resulting LiCl suitable for use in lithium metal extraction or the preparation of other lithium compounds, including lithium carbonate and lithium hydroxide monohydrate, for use in lithium ion battery applications.
The process of the present invention has as one object thereof to overcome substantially one or more of the above mentioned problems associated with the prior art, or to at least provide a useful alternative thereto.
The preceding discussion of the background art is intended to facilitate an understanding of the present invention only. This discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge as at the priority date of the application.
Throughout the specification and claims, unless the context requires otherwise, the word “comprise” or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.
The term brine, or brines, or variations thereof, is to be understood to include a solution of alkali and/or alkaline earth metal salt(s) in water, of a natural or possibly industrial source. The concentrations of the various salts can vary widely. The ions present in brine may include a combination of one or more of a monovalent cation, such as lithium, multivalent cations, monovalent anions, and multivalent anions.
The term high purity lithium chloride solution is to be understood, unless the context requires otherwise, as requiring any impurity present to be present in amounts of less than about 20 ppm.
Throughout the specification and claims, unless the context requires otherwise, the term titanate or titanate adsorbent, or variations thereof, are to be understood to include inorganic compounds composed of titanium oxides, particularly hydrated titanium dioxide, hydrogen titanate and sodium titanate.